1. Field of the Invention
The present invention relates to a waste toner conveying device, and an image forming apparatus using the waste toner conveying device.
2. Description of the Related Art
Conventional image forming apparatuses with image carriers such as a photosensitive element and an intermediate transfer element, include a cleaning device that collects residual waste toner on the image carriers. Waste toner collected by the cleaning device is conveyed to a waste toner container by a waste toner conveying device provided in the apparatus main body separately from the cleaning device.
Some of waste toner conveying devices conveys toner through a conveying path including a falling and conveying path for falling waste toner under its own weight. However, in such a waste toner conveying device, in particular in hot and humid conditions, waste toner having passed through the falling and conveying path is prone to adhere to the inner wall of a housing constituting the falling and conveying path, and over time the waste toner coagulates and gradually accumulates. Thus, the accumulated waste toner gradually clogs the falling and conveying path, that is, so-called toner bridging occurs, which interferes with collection of waste toner.
Japanese Patent No. 3893232 suggests a waste toner conveying device in which a thin plate-like swing member is provided along one side surface of inner wall surfaces of a housing constituting a falling and conveying path. In the waste toner conveying device, swinging of the swing member swings prevents occurrence of a toner bridging state in which toner adheres to and grows in the interior of the housing constituting the falling and conveying path. The swing member is swung by a rotational drive shaft and a drive transfer unit formed by an eccentric cam rotating integrally with the rotational drive shaft. The lower end portion of the swing member abuts the eccentric cam, and the rotation of the eccentric cam swings and drives the swing member. At that time, the drive transfer member formed by the eccentric cam is laterally separated from the falling and conveying path at the lower end portion of the swing member. This makes it possible to prevent that toner is sandwiched between the abutment part of the swing member and the eccentric cam, and prevent that the toner is pressed and heated by sliding of the swing member and the eccentric cam, and thus coagulate into lumps.
However, if there is any limitation imposed on the size of a waste toner conveying device, the waste toner conveying device may need to be reduced in size. In such a case, if the swinging drive transfer unit is to be separated from the falling and conveying path as described in Japanese Patent No. 3893232, the falling and conveying path need to be made narrower accordingly. Thus, when the waste toner conveying device is reduced in size, it is difficult to reliably prevent occurrence of toner bridging in the falling and conveying path even if the toner bridging prevention member is disposed in the falling and conveying path.
Therefore, there is a need to provide a waste toner conveying device that, if being reduced in size, reliably prevents occurrence of toner bridging and coagulation in the falling and conveying path of the waste toner conveying path, and an image forming apparatus using the waste toner conveying device.